1. Technical Field
The present invention relates to an apparatus for supporting and following the movement of a part of a person's body, and in particular, to an apparatus for supporting and following the movement of a part of a person's body, which is provided with a load device on which a part of a person's body is to be placed (i.e., loaded), the apparatus including an operating mode for permitting the load device to follow the movement of a part of a person's body and an operating mode for limiting the movement of the load device.
2. Related Art
A work that requires delicate hand operation, such as a neurosurgical operation, may involve the use of an apparatus for supporting and following the movement of a part of a person's body, to use the apparatus to support an arm of the worker. In such an apparatus, when the worker wishes to move the worker's arm, a support for supporting the arm is required to follow the movement of the arm. Also, when the worker wishes to lock the worker's arm, the support is required to be locked. For this purpose, JP-A-H10-272163, for example, suggests that a surgeon's arm, for example, be fastened to a support via a belt member, the support being provided at a distal end of a movable articulated holding arm. Thus, the support is permitted to follow the movement of the surgeon's arm. Further, when a foot switch is operated, the articulated holding arm is prohibited from moving to thereby lock the support.
However, in the apparatus disclosed in JP-A-H10-272163, the surgeon has to unfasten the belt member every time the surgeon is required to remove his/her arm from the support to temporarily place a surgical tool, such as tweezers, on a work table or the like, and thus the operability is impaired. In this regard, JP-A-2009-291363 suggests use of an arm rest (corresponding to the support of JP-A-H10-272163) supported by a multijoint arm. Specifically, the multijoint arm is applied with a force so that the arm rest is urged upward to thereby press the arm rest against the surgeon's arm from below. Thus, the arm rest is permitted to follow the movement of the surgeon's arm. In this case, when the movement of the multijoint arm is prohibited to lock the arm rest, the surgeon can easily carry out the surgery while placing his/her arm on the arm rest, or can easily remove his/her arm from the arm rest.
However, in the apparatus disclosed in JP-A-2009-291363, when the arm rest is permitted to move with the movement of the surgeon's arm, the surgeon's arm is constantly pressed upward by the arm rest. Therefore, for example, when the surgeon desires to move his/her arm downward, he/she has to move his/her arm against the pressing force of the arm rest. Thus, the pressing force of the arm rest could prevent the smooth procedure of the surgery. Further, JP-A-2009-291363 suggests detecting the force applied to the arm rest from the surgeon's arm to release braking applied by a brake. However, in this case, the surgeon's arm is required to be prevented from being abruptly pressed by the arm rest immediately after the release.
As a measure against this, the applicants of the present so invention suggest providing a securing member to the base (corresponding to the support of JP-A-H10-272163) which is movably supported by a support that includes a brake and a balancing mechanism to thereby secure the arm of the surgeon. As disclosed in Japanese Patent Application No. 2012-158125 in particular, the applicants further suggest that the operating mode be switched as follows. Specifically, according to this patent application, when the operating mode is switched to free mode, the surgeon's arm is secured to the base by the securing member. Further, in the free mode, the limitation in the movement of the base imposed by the brake is released. Therefore, without the surgeon's necessity of putting so much strength into his/her arm, the base will follow the movement of the surgeon's arm. On the other hand, in a limiting mode, the securing of the surgeon's arm by the securing member is released, while the movement of the base is limited by the brake. Therefore, when the surgeon's arm is moved on the base or removed from the base, the position of the base is retained.
According to the technique of the patent application set forth above, it is true that a part of a person's body, such as an arm, can be freely moved, including removal of a part of a person's body from the base, when the operating mode is limiting mode. However, when a surgeon, for example, wishes to only slightly move his/her arm, with his/her arm being placed on the base, the ease of the movement of his/her arm is still insufficient and there is room for improvement in the easiness. JP-A-2009-291363 suggests that a micromotion mode be provided to such an apparatus to control a powder brake, for example, for little-by-little movement of the base. However, in this case, the number of required actuators or sensors is increased to complicate the configuration and the control of the apparatus.